The present invention relates generally to screw retention devices, and more particularly to a screw retention device having a serrated holding portion for engagement with corresponding serrations on a screw to be retained.
When using a fastener, such as a screw, there is a risk that vibrations, or other conditions, will cause the screw to shift in position, loosen and, in some cases, fall out. To prevent the screw from shifting or falling out, numerous screw retention devices and methods have been developed. As shown in FIG. 4, a known device 200 is disclosed for preventing fall out. The device 200 includes a wiring mechanism 202 that is used to wire a pair of tightened screw heads 204, 206 together.
Another known device 220 is shown in FIGS. 5a-5c. The known device 220 includes a tightening plate 222, best shown in FIG. 5a, having a pair of holes 224 dimensioned to receive screws 226. The screws 226, as best shown in FIG. 5b, have a triangular head portion 228 and a threaded shaft 230. To install the tightening plate 222, the screw shaft 230 is positioned through a hole 224 of the tightening plate 222 prior to being threadingly engaged with another object. As shown in FIG. 5c, each tightening plate 222 receives two screws 226. When the screws are fastened, the edge 232 of the tightening plate 222 is bent in the direction designated as X, shown in FIG. 5c, to fit the shape of the screw. When the edges 232 are bent around the screw 226, the bent edges prevent the triangular head 228 from rotating. Thus, the screw 226 is maintained in position.
The known methods of retaining screws in a static position are complicated and time consuming. Accordingly, there is a need for a simplified method and device to retain screws in a static position.
A screw retention device is disclosed for maintaining at least a pair of screws in a substantially static position. The term screw is used herein to refer to any fastener that threadingly engages an object. The screw retention device preferably includes at least two clamping portions, each clamping portion defining a recess therein for receiving and securely retaining a screw. The clamping portions include a serrated surface extending circumferentially around an inside periphery of the clamping portion, surrounding the recess. The serrated surface of the clamping portion corresponds to and engages with a serrated surface on the screw to retain the screw. In a preferred embodiment of the invention, the screw retention device is press fitted onto the screws.
In one embodiment of the invention, the serrated surface of the clamping portion extends around the entire inside periphery of the clamping portion and the serrated surface of the screw extends around the entire outside periphery of the screw. The screw retention device is snap fit onto the screws and the serrated surface of the clamping portions engage the serrated surface of the screws.
The screws preferably have a conical head portion to facilitate the installation of the screw retention device. During installation, the clamping portions slide down the conical head portion of the screw until the serrated surface of the clamping portions engages the serrated surface of the screw. In a more preferred embodiment, the conical head portion of the screw is dimensioned to overlap the top surface of the screw retention device when the device is installed, and restrict the movement of the device in the direction of the axis of the screw.
The screw retention device is preferably made of an elastic material that provides elastic yield during the installation of the device. In one embodiment of the invention, the screw retention device comprises rubber. In another embodiment of the invention, the screw retention device comprises a relatively harder material, such as plastic. If a relatively harder material is used, slits are provided in the screw retention device, extending from the recess, to facilitate the installation of the device.
In another preferred embodiment of the invention, the clamping portions include a serrated surface and a non-serrated surface on the inside periphery surrounding the recess. The non-serrated surface is preferably disposed proximal the slit. To facilitate the removal of the screw retention device from the screws, the clamping portions preferably include a pair of extension handles. The extension handles operate such that by pulling the handles apart, the recess is expanded and the serrated surface of the clamping portion disengages from the serrated surface of the screw.
Other objects, features and advantages of the present invention will become apparent to those skilled in the art from the following detailed description. It is to be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not limitation. Many changes and modifications within the scope of the present invention may be made without departing from the spirit thereof, and the invention includes all such modifications.